A probe head is used in metrology applications as an adaptor for attachment of a measurement probe to a localiser such as co-ordinate measurement machine. Examples of probe heads include the PH-10 series manufactured by Renishaw. Advantageously, the probe head further serves to angularly orientate the measurement probe relative to the end effector of the co-ordinate measurement machine; typically a probe head has two axes of rotation, optionally be motorised. However, the probe head lacks full flexibility of a third axis of rotation that would allow position of the measurement probe toward the object to be measured. In the art, this is generally solved using a second adaptor connecting the probe head to the measurement probe that provides a further axis of rotation. The prior art describes probe alternative position adjustment mechanisms, for instance, U.S. Pat. No. 5,848,477 discloses a passive contact probe attached to a ball and socket joint having a plurality of discrete selectable angles; the instability of a ball and socket arrangement renders it suitable for the majority of measurement probes. U.S. Pat. No. 5,778,548 discloses a removable measurement probe attached to a probe head, that lacks the flexibility of three rotational axes. WO 2009/016185 discloses a linear scanning laser sensor provided with a fixed connector. The second adaptor is not ideal as it introduces a levering effect, destabilising positions set by the probe head and the localiser, thereby imposing weight restrictions on the measurement probe. In particular, for an optical measurement probe, the restrictions on the lens size and weight lead to a reduction in accuracy. Moreover, the second adaptor introduces additional complexity in subsequent calculations. It can also be a source of signal loss or reduction. Hence, it is an aim of the invention to overcome the problems of the art.